Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c

From	Matthias Kaehlcke <mka@chromium.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c
Date	2017-06-23 00:40 +0200
Message-ID	<tViVz-2hN-7@gated-at.bofh.it> (permalink)
References	<tlNWh-6eK-9@gated-at.bofh.it> <tlNWh-6eK-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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(removed some non-x86 lists and folks from recipients)

El Thu, Mar 16, 2017 at 05:15:17PM -0700 Michael Davidson ha dit:

> undef memcpy and friends in boot/string.c so that the functions
> defined here will have the correct names, otherwise we end up
> up trying to redefine __builtin_memcpy etc.
> Surprisingly, gcc allows this (and, helpfully, discards the
> __builtin_ prefix from the function name when compiling it),
> but clang does not.
> 
> Adding these #undef's appears to preserve what I assume was
> the original intent of the code.

Any comments on this patch?

> Signed-off-by: Michael Davidson <md@google.com>
> ---
>  arch/x86/boot/string.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
> index 5457b02fc050..b40266850869 100644
> --- a/arch/x86/boot/string.c
> +++ b/arch/x86/boot/string.c
> @@ -16,6 +16,15 @@
>  #include "ctype.h"
>  #include "string.h"
>  
> +/*
> + * Undef these macros so that the functions that we provide
> + * here will have the correct names regardless of how string.h
> + * may have chosen to #define them.
> + */
> +#undef memcpy
> +#undef memset
> +#undef memcmp
> +
>  int memcmp(const void *s1, const void *s2, size_t len)
>  {
>  	bool diff;

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Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c Matthias Kaehlcke <mka@chromium.org> - 2017-06-23 00:40 +0200
  Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c "H. Peter Anvin" <hpa@zytor.com> - 2017-06-23 00:50 +0200
    Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c Matthias Kaehlcke <mka@chromium.org> - 2017-06-30 20:40 +0200

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